In 2003, the  northeastern U.S. suffered the largest power blackout in the nation’s history. For two days, 50 million subscribers in eight  states and parts of Ontario lost power, resulting in an estimated $6 billion in  economic losses. The primary cause of the outage?  An inability to recognize, assess, and understand  the inadequacies and deterioration of parts of the power grid over wide areas,  a story not unfamiliar to critical infrastructure management. From reputation  damage and expensive penalties to direct financial losses into the billions of  dollars, network reliability at the critical infrastructure level was (and  still is) a top concern in the utilities industry.

In addition  to causing system and equipment damage that is costly to repair, faults on the  power system can result in disturbances to normal system operations. Serious  disturbances can even result in the loss of system stability and large-scale  blackouts. Fault clearing is therefore an integral component of power  transmission and distribution system design, maintenance, and operations. The protection  schemes designed to identify and clear faults address a variety of objectives  across the network:

• Remove the faulty element from the rest of the  system.
• Limit or prevent equipment damage.
• Prevent severe power swings or system  instability.
• Minimize adverse effects on customer loads.
• Maintain power system transfer capability.

Schemes, Apps, and Convergence
One type of  scheme that is commonly implemented in power utility substations is a  communications-assisted protection scheme across the wide-area network (WAN).  This type of scheme facilitates data sharing between protection devices and  makes it possible to employ methods that improve the scheme’s dependability,  selectivity, security, and speed. Reliable communications enable the implementation  of differential comparison schemes, such as line current differential (87L)  protection.

Wide-area  networks (WANs) are used to carry the relay protection multiplexed channels in  addition to other substation services (voice, teleprotection, telemetry, video,  control and automation, email, and corporate local-area network (LAN)) and have  become an integral and necessary part of modern power network protection  systems.

Time-division  multiplexing (TDM/SONET) has been widely adopted across the power utility industry  as the preferred WAN transport technology because it provides low-latency,  deterministic, and minimal-asymmetry performance. However, there is a clear  trend within the industry to move toward using Ethernet and packet-based  networking for all power utility applications and services, including  protection. The  motivation to move away from TDM-based systems, especially synchronous optical  network-based (SONET) and synchronous digital hierarchy (SDH) systems, is  driven by a desire to converge information technology (IT) and operational  technology (OT) networks and standardize on a common set of interfaces to  reduce capital and operating expenses. The migration to packet-based networking  technologies such as Carrier Ethernet has created the challenge of engineering  teleprotection services to provide the determinism and guaranteed performance  required by protection applications.

The motivation to move away from TDM-based systems, especially synchronous optical network-based (SONET) and synchronous digital hierarchy (SDH) systems, is driven by a desire to converge information technology (IT) and operational technology (OT) networks and standardize on a common set of interfaces to reduce capital and operating expenses.

Avoiding  another power outage like the one experienced in 2003 requires a solution with  ultra low latency and failover performance If a power system fault occurs, communications-assisted  protection schemes across the WAN operate to isolate the fault and prevent  instability around the failure. A fault can occur in the order of milliseconds  and if not detected and communicated with the lowest of latencies, equipment  damage and larger portions of the power grid could be effected.

To address  these challenges, Ciena has partnered with a best in class solution for the  power substation delivered by Schweitzer Engineering  Labs.

The SEL  Integrated Communications Optical Network (ICON) deterministic packet transport  solution provides the innovative approach of delivering mission-critical  traffic with low and deterministic latency over a Ciena Carrier Ethernet  transport network. The concept is to preserve the performance characteristics  of TDM, which are presently available in the ICON synchronous optical network  (SONET) platform, with no performance degradation when transported over Carrier  Ethernet as a WAN transport protocol.

Want to learn more? Watch this on-demand webinar to learn how Ciena and SEL are partnering to provide an end-to-end solution for utility networks, and how SEL and Ciena Carrier Ethernet technology interoperate to provide deterministic performance (guaranteed latency) for critical traffic over Carrier Ethernet-based Wide Area Networks (WANs) including the ability of the solution to support a line current differential protection channel across a Carrier Ethernet topology.